Synthesis and structural studies of rhenium(I) tricarbonyl complexes with thione containing chelators

Sodium dihydrobis(2-mercaptothiazolyl)borate, Na[H2B(tiaz)(2)], reacts with (NEt4)(2)[Re(CO)(3)Br-3] in water to afford fac-[Re{kappa(3)-H(mu-H)B(tiaz)(2)}(CO)(3)] (1). In a similar manner, treatment of the same Re(I) starting material with bis(2-mercaptoimidazolyl)methane, H2C(tim(Me))(2), yields fac-[ReBr{kappa(2)-H2C(tim(Me))(2)}(CO)(3)] (2). The organometallic complexes 1 and 2 have been characterized by IR, H-1 and C-13 NMR spectroscopy, and also by X-ray crystallographic analysis. X-ray diffraction analysis revealed the presence of a short B-H center dot center dot center dot Re interaction in the case of 1, and the absence of C-H center dot center dot center dot Re interactions in the crystal structure of 2. For both compounds the rhenium atom adopts a slightly distorted octahedral coordination with a facial arrangement of the carbonyl ligands. The three remaining coordination positions are occupied by the two thione sulfur atoms from the anchor ligands, and by an agostic hydride (1) or a bromide ligand (2). Compound 1 is highly stable either in the solid state or in solution. In particular, its B-H center dot center dot center dot Re interaction is retained in solution, even in coordinating solvents, namely acetonitrile, dimethylsulfoxide and tetrahydrofuran. Unlike 1, compound 2 is only moderately stable in acetonitrile, undergoing a slow release of the bis(2-mercaptoimidazolyl)methane. (c) 2006 Elsevier B.V. All rights reserved.